MONTARA (AP) — A California congresswoman wants an independent investigator to determine whether a federal park ranger used excessive force when she fired a stun gun on a man walking his dogs.

Gary Hesterberg, 50, was stunned with a Taser electric-shock device when he was walking two small dogs off-leash in violation of rules at the Golden Gate National Recreational Area, park officials have said.

In a letter Wednesday to the park Superintendent Frank Dean, Rep. Jackie Speier said the ranger's use of the stun gun appears to be unwarranted. "Many of my constituents are understandably angered by what appears to be an excessive use of force by a park ranger," the Hillsborough Democrat wrote.

Speier said she wants more information about what happened, what training park rangers receive for stun-gun use and whether there are enough notices about leash rules.

The National Park Service planned to answer to Speier's questions by week's end, said park spokesman Howard Levitt, according to the San Francisco Chronicle (http://bit.ly/wDRc1A ).

The incident occurred near Montara in a newly incorporated part of the national recreational area in San Mateo County. Hesterberg gave the ranger a false name, challenged her authority and refused repeated orders to remain at the scene, Levitt said.

Hesterberg told the ranger not to stun him because he had a heart condition before he turned to walk away, according to witness and official accounts. The ranger then shot him in the back with the Taser.

Paramedics checked out Hesterberg at the scene before he was arrested on suspicion of failing to obey a lawful order, having dogs off-leash and knowingly providing false information, Levitt said. He was later released.

The park service is conducting its own inquiry, officials said. The ranger who fired the stun gun remains on the job, Levitt said.